Signaling optimization in 3GPP analytics

ABSTRACT

The invention relates to methods of providing requested network information from a first core Network Function (NF) to a second NF, and devices performing the methods. In an aspect, a method performed by a first core NF entity of providing requested network information to a second NF entity is provided. The method comprises receiving a request to obtain the network information originating from the second NF entity, determining an expiry time stipulating how long the requested network information is valid, and transmitting, towards the second NF entity, the requested network information and the expiry time.

This application is a continuation of U.S. application Ser. No.17/055,107, filed Nov. 12, 2020, now U.S. Pat. No. 11,290,897 B2, whichis a 35 U.S.C. § 371 national phase filing of International ApplicationNo. PCT/EP2018/062528, filed May 15, 2018, the disclosures of which areincorporated herein by reference in their entireties.

TECHNICAL FIELD

The invention relates to methods of providing requested networkinformation from a first core Network Function (NF) to a second NF, anddevices performing the methods.

BACKGROUND

The fifth generation (5G) System architecture being standardized by 3rdGeneration Partnership Project (3GPP) is defined to support dataconnectivity and services enabling deployments to use techniques such ase.g. Network Function Virtualization (NFV) and Software DefinedNetworking (SDN).

FIG. 1 illustrates a 5G core network comprising a plurality of so calledNetwork Functions (NFs) or core network function entities, such as aUnified Data Repository (UDR, 10) for storing subscription data andpolicy data, a Network Exposure Function (NEF, 11) for exposingcapabilities and events, and an Access and Mobility Management Function(AMF, 12) configured to manage registration, connection, reachability,mobility, etc.

Further, the 5G core network comprises a Network Data Analytics Function(NWDAF, 13) which represents an operator managed network analyticslogical function. The NWDAF is discussed for instance in 3GPPspecification TS 23.502. The NWDAF is an example of a network functionentity that provides network information such as slice specific networkdata analytics to other network function entities such as Policy ControlFunction (PCF, 14) and Network Slice Selection Function (NSSF, 15). TheNWDAF 13 provides network analytics information (i.e., load levelinformation) to the PCF 14 and the NSSF 15 on a network slice instancelevel and the NWDAF 13 is not required to be aware of the currentsubscribers using the slice. The NWDAF 13 notifies/publishes slicespecific network status analytic information to the PCF(s) and NSSF thatare subscribed to it. The PCF(s) and NSSF may collect directly slicespecific network status analytic information from NWDAF. Thisinformation is not subscriber specific. The PCF 14 uses that data in itspolicy decisions. The NSSF 15 may use the load level informationprovided by the NWDAF 13 for slice selection, i.e. which slices are toserve a User Equipment (UE) such as for instance a mobile phone.

Moreover, an Application Function (AF, 16) supports applicationinfluence on traffic routing, a Session Management function (SMF, 17) isconfigured to perform session management, e.g. session establishment,modify and release, etc., and a User Plane Function (UPF, 18) is aservice function that processes user plane packets; processing mayinclude altering the packet's payload and/or header, interconnection todata network(s), packet routing and forwarding, etc. It is noted thatfurther NFs than those illustrated in FIG. 1 may be included in the 5Gcore network.

In the core network, an NF may subscribe to the NWDAF to periodicallyreceive network analytics information, or to request and receive theinformation instantly

A problem of the current solution is the potentially unnecessarysignaling load created in the core network. Some network analyticsinformation may not change significantly over time, and may even bestatic. Hence, the same information (or a very similar one) would beprovided repeatedly, entailing redundant signaling in the network.

SUMMARY

An object of the invention is to solve, or at least mitigate, thisproblem and thus to provide a method in a core network of providingrequested network analytics information from an NWDAF to an NF.

This object is attained in a first aspect of the invention by a methodperformed by a first core NF entity of providing requested networkinformation to a second NF entity. The method comprises receiving arequest to obtain the network information originating from the second NFentity, determining an expiry time stipulating how long the requestednetwork information is valid, and transmitting, towards the second NFentity, the requested network information and the expiry time.

This object is attained in a second aspect of the invention by a firstcore NF entity configured to provide requested network information to asecond NF entity, the first core NF entity comprising a processing unitand a memory, said memory containing instructions executable by saidprocessing unit, whereby the first core NF entity is operative toreceive a request to obtain the network information originating from thesecond NF entity, determine an expiry time stipulating how long therequested network information is valid, and to transmit, towards thesecond NF entity, the requested network information and the expiry time.

This object is attained in a third aspect of the invention by a methodperformed by a requesting NF entity of obtaining network information ofa responding core NF entity. The method comprises transmitting, towardsthe responding core NF entity, a request to obtain the networkinformation, and receiving the requested network information and anexpiry time determined by the responding core NF entity stipulating howlong the requested network information is valid.

This object is attained in a fourth aspect of the invention by arequesting NF entity configured to obtaining network information of aresponding core NF entity, the requesting NF entity comprising aprocessing unit and a memory, said memory containing instructionsexecutable by said processing unit, whereby the requesting NF entity isoperative to transmit towards the responding core NF entity, a requestto obtain the network information, and to receive the requested networkinformation and an expiry time determined by the responding core NFentity stipulating how long the requested network information is valid.

This object is attained in a fifth aspect of the invention by a methodperformed by a proxy device of providing requested network informationof a first core NF entity, to a second NF entity. The method comprisesreceiving, from the second NF entity, a request to obtain the networkinformation, transmitting, to the first core NF entity, the request toobtain the network information, receiving, from the first core NFentity, the requested network information and an expiry time determinedby the first core NF entity stipulating how long the requested networkinformation is valid, and transmitting, to the second NF entity, therequested network information.

This object is attained in a sixth aspect of the invention by a proxydevice configured to provide requested network information of a firstcore NF entity, to a second NF entity, the proxy device comprising aprocessing unit and a memory, said memory containing instructionsexecutable by said processing unit, whereby the proxy device isoperative to receive, from the second NF entity, a request to obtain thenetwork information, transmit, to the first core NF entity, the requestto obtain the network information, receive, from the first core NFentity, the requested network information and an expiry time determinedby the first core NF entity stipulating how long the requested networkinformation is valid, and to transmit, to the second NF entity, therequested network information.

In an aspect, a requesting NF entity sends a request to obtain networkinformation, also referred to as network analytics information, to aresponding core NF entity. As an example, the requesting NF entityrequests an indication of traffic load during a particular day of theweek for one or more network slices instances handled by the respondingcore NF entity. Hence, the request comprises an indicator specifying theparticular network information.

Upon receiving the request from the requesting NF entity, the respondingcore NF entity acquires the requested network information (e.g. from alocal storage) and associates an expiry time with the requested networkinformation indicating how long the requested network information isvalid.

Thereafter, the responding core NF entity sends the requested networkinformation and the associated expiry time to the requesting NF entity.

Advantageously, with the expiry time associated with the requestednetwork information, the requesting NF entity may come to a number ofconclusions. For instance, the requesting NF entity may (1) concludethat it is not necessary to request the information again until theexpiry time has expired in the case of a request/response operation, or(2) update a periodicity with which it expects to receive the requestednetwork analytics information in the case of a subscribe/notifyoperation. In (1), the invention enables reducing unnecessary signallingbetween the responding core NF entity and the NF(s) requesting thenetwork analytics information. In (2), if the expiry time is longer thanthe periodicity with which the NF(s) wish to subscribe to the requestedinformation, unnecessary signalling is avoided, while if the expiry timeis shorter than the periodicity with which the NF(s) wish to subscribeto the requested information, up-to-date information will be received atthe NF(s).

In an embodiment, the request sent from the requesting NF entity furthercomprises at least one of: at least one identifier identifying a networkslice instance for which the request is made, and at least oneidentifier identifying a user device or a group of user devices forwhich the request is made.

In another embodiment, the request sent from the requesting NF entityfurther comprises an indication of periodicity with which the requestnetwork information is to be obtained, wherein the responding core NFentity transmits the requested network information with a periodicitystipulated by the determined expiry time.

In a further embodiment, the responding core NF entity sends a messagetowards the requesting NF entity comprising a recommended periodicitystipulated by the determined expiry time, wherein the requesting NFentity sends a confirmation indicating whether the recommendedperiodicity stipulated by the determined expiry time should be used ornot.

In another embodiment, the responding core NF entity sends an updatemessage towards the second NF entity, in case it is determined that theexpiry time for the requested network information has changed, theupdate message comprising a recommended periodicity stipulated by thedetermined changed expiry time; wherein the requesting NF entity sends aconfirmation indicating whether the recommended periodicity stipulatedby the determined changed expiry time should be used or not.

In yet an embodiment, the request originating from the requesting NFentity to obtain the network information is received the responding coreNF entity via a proxy device to which the requested network informationand the expiry time is transmitted for forwarding to the second NFentity (14, 15).

In an embodiment, the requesting NF entity will refrain from makinganother request for said network information as long as the expiry timehas not elapsed.

In yet an embodiment, the requesting NF entity stores the receivednetwork information and the expiry time.

In a further aspect, a requesting NF entity sends a request to obtainnetwork information, via a proxy device forwarding the request, to aresponding core NF entity.

In response thereto, the responding core NF entity determines the expirytime for the requested network information and sends a response messageto the proxy device comprising the requested network information and theexpiry time. The proxy device then stores the received information andforwards the requested network information to the requesting NF entity.

Now, assuming that a further NF entity wishes to obtain the same networkinformation as was just delivered to the requesting and the proxydevice; the further NF entity will then send a request to the proxydevice which will deliver the requested network information, given thatthe expiry time has not elapsed.

In a seventh aspect of the invention, a computer program is providedcomprising computer-executable instructions for causing a first core NFentity to perform steps recited in the method of the first aspect whenthe computer-executable instructions are executed on a processing unitincluded in the first core NF entity.

In an eight aspect of the invention, a computer program product isprovided comprising a computer readable medium, the computer readablemedium having the computer program of the seventh aspect embodiedthereon.

In a ninth aspect of the invention, a computer program is providedcomprising computer-executable instructions for causing a requesting NFentity to perform steps recited in the method of the third aspect whenthe computer-executable instructions are executed on a processing unitincluded in the requesting NF entity.

In a tenth aspect of the invention, a computer program product isprovided comprising a computer readable medium, the computer readablemedium having the computer program of the ninth aspect embodied thereon.

In an eleventh aspect of the invention, a computer program is providedcomprising computer-executable instructions for causing a proxy deviceto perform steps recited in the method of the fifth aspect when thecomputer-executable instructions are executed on a processing unitincluded in the proxy device.

In a twelfth aspect of the invention, a computer program product isprovided comprising a computer readable medium, the computer readablemedium having the computer program of the eleventh aspect embodiedthereon.

Generally, all terms used in the claims are to be interpreted accordingto their ordinary meaning in the technical field, unless explicitlydefined otherwise herein. All references to “a/an/the element,apparatus, component, means, step, etc.” are to be interpreted openly asreferring to at least one instance of the element, apparatus, component,means, step, etc., unless explicitly stated otherwise. The steps of anymethod disclosed herein do not have to be performed in the exact orderdisclosed, unless explicitly stated.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is now described, by way of example, with reference to theaccompanying drawings, in which:

FIG. 1 illustrates a 5G core network in which the invention may beimplemented;

FIG. 2 shows a signalling diagram illustrating a method performed by afirst, responding core NF entity of providing network analyticsinformation to a second NF entity requesting the network analyticsinformation according to an embodiment;

FIG. 3 shows a signalling diagram illustrating a method performed by afirst, responding core NF entity of providing network analyticsinformation to a second NF entity requesting the network analyticsinformation according to another embodiment;

FIG. 4 shows a signalling diagram illustrating a method performed by afirst, responding core NF entity of providing network analyticsinformation to a second NF entity requesting the network analyticsinformation according to yet another embodiment;

FIG. 5 shows a signalling diagram illustrating a method performed by afirst, responding core NF entity of providing network analyticsinformation to a second NF entity requesting the network analyticsinformation according to a further embodiment;

FIG. 6 shows a signalling diagram illustrating a method performed by afirst, responding core NF entity of providing network analyticsinformation to a second NF entity requesting the network analyticsinformation according to still a further embodiment;

FIGS. 7A and 7B show a signalling diagram illustrating a methodperformed by a first, responding core NF entity of providing, via aproxy device, network analytics information to a second NF entityrequesting the network analytics information according to an embodiment;

FIG. 8 illustrates a first core NF entity according to an embodiment;

FIG. 9 illustrates a second NF entity according to an embodiment; and

FIG. 10 illustrates a proxy device according to another embodiment.

DETAILED DESCRIPTION

The invention will now be described more fully hereinafter withreference to the accompanying drawings, in which certain embodiments ofthe invention are shown. This invention may, however, be embodied inmany different forms and should not be construed as limited to theembodiments set forth herein; rather, these embodiments are provided byway of example so that this disclosure will be thorough and complete,and will fully convey the scope of the invention to those skilled in theart. Like numbers refer to like elements throughout the description.

FIG. 1 illustrates a 5G core network and the NFs included have beendiscussed previously.

Now, the NWDAF 13 is responsible for providing network analyticsinformation upon request or subscription from NFs. For example, an NFmay request specific analytics information on the load level of aparticular network slice.

In an example, the load level information provided by the NWDAF 13 mayindicate that traffic load of a particular slice is relatively high at aparticular time window of a certain day of the week, such as e.g.between 09:00 and 10:00 on a Monday, in which case the NF receiving theload level information, for instance the PCF 14 or the NSSF 15, mayselect another network slice for UE(s) served by the PCF/NSSF.

The PCF 14 or NSSF 15 may either subscribe to receive the load levelinformation on a periodical basis or if a particular load levelthreshold is exceeded, or actively submit a request to instantly receivethe load level information.

Hence, as defined in 3GPP specifications, the NWDAF 13 (the serviceprovider) provides analytics insights (e.g. load level information)either by means of a subscribe/notify operation or a request/responseoperation (to the service consumer).

Further examples as to what information could constitute networkanalytics information are one or more of: (a) application usage andcapacity patterns at certain location or at certain time interval/typeof day or combination thereof, and (b) most used routes (by measureusers movements) to e.g. predict upcoming load.

Further examples are user specific information such as: (c) most usedapplication for a specific user at specific location and/or time, (d) aspecific user's routes (location and time), to predict next location forthe user to e.g. improved paging, (e) specific user's data usage forpreventive downloads, and (f) a specific user's most visited locationsfor identifying his/hers most suited registration areas.

In the subscribe/notify case, the NWDAF 13 provides insights to thesubscribed consumer:

-   -   (a) periodically (period value provided by the consumer in the        subscription request), or    -   (b) when the insight value changes exceed a certain threshold        value (the threshold value is provided by the consumer as well).

In the request/response case, the NWDAF 13 provides the insight:

-   -   (c) each time it receives a request from any of the        authenticated consumers.

The main problem of the current solution is the potentially unnecessarysignaling load created in options (a) and (c). Some insights may notchange significantly over time, and may even be static. In this case thesame insight value (or a very similar one) would be provided repeatedly,entailing redundant signaling in the network.

FIG. 2 shows a signalling diagram illustrating a method performed by afirst, responding core NF entity, exemplified throughout the descriptionin the form of the NWDAF 13, of providing network analytics informationto a second NF entity requesting the network analytics informationaccording to an embodiment, in this case exemplified throughout thedescription by the PCF 14 for policy decisions. It is noted that thesecond, requesting NF entity not necessarily is located in the corenetwork, but could alternatively be embodied by a non-core networkentity such as an AF 16.

In a first step 101, the PCF 14 sends a request to obtain networkanalytics information to the NWDAF 13. As an example, the PCF 14requests an indication of traffic load during a particular day of theweek for one or more network slices instances handled by the NWDAF 13.Hence, the request comprises an Analytic ID specifying the particularnetwork analytics information requested and optionally in an embodimenta Slice instance ID identifying one or more slice instances for whichthe request is made.

Upon receiving the request from the PCF 14, the NWDAF 13 acquires therequested network analytics information (e.g. from a local storage) andassociates an expiry time with the requested network analyticsinformation in step S102 indicating how long the requested networkanalytics information is valid. The expiry time will throughout thedrawings be denoted “ET”. Thereafter, in step S103, the NWDAF 13 sendsthe requested network analytics information and the associated expirytime to the PCF 14.

Advantageously, with the expiry time associated with the requestednetwork analytics information, the PCF 14 may come to a number ofconclusions. For instance, the PCF 14 may (1) conclude that it is notnecessary to request the information again until the expiry time hasexpired in the case of a request/response operation, or (2) update theperiodicity with which it expects to receive the requested networkanalytics information in the case of a subscribe/notify operation. In(1), the invention enables reducing unnecessary signalling between theNWDAF 13 and the NF(s) requesting the network analytics information. In(2), if the expiry time is longer than the periodicity with which theNF(s) wish to subscribe to the requested information, unnecessarysignalling is avoided, while if the expiry time is shorter than theperiodicity with which the NF(s) wish to subscribe to the requestedinformation, up-to-date information will be received at the NF(s).

In an embodiment, the request transmitted from the PCF 14 in step S101further comprises a User ID or a User Group ID indicating a single userdevice or a group of user devices for which the request for networkanalytics information is made. Advantageously, this provides forhandling the NWDAF analytics information per user or user group. To thatextent, an NF can retrieve analytics information for a specific userdevice or group of user devices.

FIG. 3 shows a signalling diagram illustrating a method performed by anNWDAF 13 in a core network of providing requested network analyticsinformation to the PCF 14 according to an embodiment.

FIG. 3 illustrates a scenario where the PCF 14 performs arequest/response operation.

In a first step S201, the PCF 14 sends a request to obtain networkanalytics information to the NWDAF 13 in the form of anNnwdaf_AnalyticsInfo_Request message to the NWDAF 13 including AnalyticID identifying the requested network analytics information, andoptionally Slice instance ID and/or User/User group ID.

In response thereto, the NWDAF 13 determines in step S202 the expirytime for the requested network analytics information and sends in stepS203 a response message to the PCF 14 including Analytic value andExpiry Time, where “Analytic value” denotes the actually requestedpayload network analytics information.

Upon receiving the response message in step S203, the PCF 14 stores thenetwork analytics information and the expiry time associated with theinformation in step S204, and optionally any Slice instance ID and/orUser/User group ID. Even though not shown in FIG. 3 , it is noted thatthe PCF 14 may send an acknowledgement to the NWDAF 13 that theinformation has been received either before or after storing theinformation in step S204.

Now, in an embodiment, as longs as the time that has elapsed since thereceiving of the requested network analytics information does not exceedthe stored expiry time, the PCF 14 will turn to stored network analyticsinformation for every user it serves as identified by means of theUser/User group ID. It is noted that the NWDAF 13 already may be awareof the particular device/group of devices identified by means of theUser/User group ID, it may not be necessary to send the User/User groupID. Further, if the PCF 14 already is aware of which device(s) thereceived network information relates to, it may not be necessary to sendthe User/User group ID

When the time that has elapsed since the receiving of the requestednetwork analytics information indeed exceeds the stored expiry time, thePCF 14 may repeat the procedure of requesting the network analyticsinformation of step S201) in which case the NWDAF 13 again willdetermine the expiry time in step S202 and send the requested networkanalytics information along with the expiry time to the PCF 14. It isnoted that the expiry time as well as the network analytics informationwith which it is associated may have changed.

FIG. 4 shows a signalling diagram illustrating a method performed by anNWDAF 13 in a core network of providing requested network analyticsinformation to the PCF 14 according to an embodiment.

FIG. 4 illustrates a scenario where the PCF 14 performs asubscribe/notify operation.

In a first step S301, the PCF 14 sends a request to obtain networkanalytics information to the NWDAF 13 in the form of anNnwdaf_EventsSubscription_Subscribe message to the NWDAF 13 includingAnalytic ID identifying the requested network analytics information, andoptionally Slice instance ID and/or User/User group ID, as well as anindication (“Period”) with which periodicity the PCF 14 wishes toreceive the requested network analytics information.

Upon receiving the request, the NWDAF 13 determines in step S302 theexpiry time for the requested network analytics information in order toset an optimal notification period for the network analytics information(identified by means of the Analytic ID).

In a first example, assuming that the PCF 14 indicates with parameterPeriod that it wishes to receive the requested network analyticsinformation every 1 minute—i.e. Period=1 minute—while the NWDAF 13concludes that the requested network analytics information is valid for2 minutes; the NWDAF 13 will thus determine that the optimalnotification period is 2 minutes. As a consequence, the NWDAF 13 willsend the requested network analytics information every 2 minutes insteadof every 1 minute, as the requested network analytics information is notlikely to have changed until the expiry time has elapsed.Advantageously, unnecessary signalling is avoided.

In a second example, assuming that the PCF 14 indicates with parameterPeriod that it wishes to receive the requested network analyticsinformation every 2 minutes—i.e. Period=2 minutes—while the NWDAF 13concludes that the requested network analytics information is valid for1 minute; the NWDAF 13 will thus determine that the optimal notificationperiod is 1 minute. As a consequence, the NWDAF 13 will send therequested network analytics information every 1 minute instead of every2 minutes, as the requested network analytics information is likely tohave changed after the expiry time has elapsed. Advantageously, the PCF14 is provided with up-to-date network analytics information. An ACKmessage may be sent from the PCF 14 to the NWDAF indicating that the PCF14 accepts the proposed shorter period. Alternatively, a NACK messagemay be sent from the PCF 14 to the NWDAF indicating that the PCF 14 doesnot accept the proposed shorter period.

In step S303, the NWDAF 13 sends the periodically requested networkanalytics information in the form of an Nnwdaf_EventsSubscription_Notifymessage to the PCF 14 including: Slice instance ID, Analytic ID,Analytic value, Expiry Time, where the “Analytic value” denotes theactually requested payload information.

Hence, the NWDAF 13 will send the requested network analyticsinformation to the PCF 14 with a periodicity stipulated by thedetermined expiry time associated with the requested network analyticsinformation. That is, in case of the first example hereinabove, theNWDAF 13 will send the requested network analytics information to thePCF 14 every 2 minutes instead of with a periodicity of 1 minute asoriginally requested by the PCF 14. As is understood, this may implythat the NWDAF 13 will wait—after having determined the expiry time instep S202—until the current 1-minute period has elapsed, if the time upuntil a next update of the analytics information is shorter then theperiodicity of the notifications.

Upon receiving the notification message in step S303, the PCF 14 maysend an acknowledgement message Ack to the NWDAF 13 in step S303 a. Thismay be particularly preferable in a scenario where the received expirytime stipulating the periodicity differs from a requested (or previouslystored) period, i.e. when any changes in periodicity occur.

Further, the PCF 14 stores in step S304 the network analyticsinformation and the expiry time associated with the information andoptionally any Slice instance ID and/or User/User group ID.

FIG. 5 shows a signalling diagram illustrating a method performed by anNWDAF 13 in a core network of providing requested network analyticsinformation to the PCF 14 according to a further embodiment.

FIG. 5 illustrates a scenario where the PCF 14 performs asubscribe/notify operation.

As in the embodiment described with reference to FIG. 4 , in a firststep S301, the PCF 14 sends a request to obtain network analyticsinformation to the NWDAF 13 in the form of anNnwdaf_EventsSubscription_Subscribe message to the NWDAF 13 includingAnalytic ID identifying the requested network analytics information, andoptionally Slice instance ID and/or User/User group ID, as well as anindication (“Period”) with which periodicity the PCF 14 wishes toreceive the requested network analytics information.

Upon receiving the request, the NWDAF 13 determines in step S302 theexpiry time for the requested network analytics information in order toset an optimal notification period for the network analyticsinformation.

Again, an example is assumed where the PCF 14 indicates with parameterPeriod that it wishes to receive the requested network analyticsinformation every 1 minute while the NWDAF 13 concludes that therequested network analytics information is valid for 2 minutes; theNWDAF 13 will thus determine that the optimal notification period is 2minutes. As a consequence, the NWDAF 13 will propose to send therequested network analytics information every 2 minutes instead of every1 minute, as the requested network analytics information is not likelyto have changed until the expiry time has elapsed. Advantageously,unnecessary signalling is avoided.

Optionally, the NWDAF 13 may acknowledge (Ack) the request in step S302a, and may further optionally include a Period recommendation along withthe Ack. In line with the above example, Period recommendation=2minutes. Advantageously, this will give the PCF 14 a possibility toreject the recommendation.

If the Period recommendation is included in the Ack, the PCF 14 may sendan update request, i.e. an Nnwdaf_EventsSubscription_Update message, instep S302 b to the NWDAF 13 to update the notification periodicity, therequest in this particular embodiment including: Slice instance ID,Analytic ID, User/User group ID, New Period (i.e. New Period=2 minutes),which update request the NWDAF 13 may acknowledge in step S302 c.

Further, the NWDAF 13 may send anNnwdaf_EventsSubscription_Period_Update message to the PCF 14 in stepS302 d including Slice instance ID, Analytic ID, User/User group ID, NewPeriod, which period update the PCF 14 may acknowledge in step S302 e.If acknowledged, the period is updated to the new period (being 2minutes). If not acknowledged, the previous period of 1 minute ismaintained.

As previously described, the NWDAF 13 may wait until the current1-minute period has elapsed and thereafter sends the periodicallyrequested network analytics information in the form of anNnwdaf_EventsSubscription_Notify message to the PCF 14 including: Sliceinstance ID, Analytic ID, Analytic value, Expire Time, where the“Analytic value” denotes the actually requested payload information instep S303.

Upon receiving the notification message in step S303, the PCF 14 maysend an acknowledgement message Ack to the NWDAF 13 in step S303 a.Further, the PCF 14 stores in step S304 the network analyticsinformation and the expiry time associated with the information, andoptionally any Slice instance ID and/or User/User group ID.

FIG. 6 shows a signalling diagram illustrating a method performed by anNWDAF 13 in a core network of providing requested network analyticsinformation to the PCF 14 according to still a further embodiment.

FIG. 6 illustrates a scenario where the PCF 14 performs asubscribe/notify operation but where the process differs somewhat fromthat described with reference to FIG. 5 . Nevertheless, up until stepS303 a, the embodiments are the same, and steps S301-S303 a will not bedescribed again.

In this embodiment, the received network analytics information is notstored following the acknowledgement in step S303 a (but will be storedlater), since the PCF 14 detects in step S303 b that the received expirytime associated with the network analytics information received in stepS303 differs from the new period that has been agreed upon through stepsS302 b-S302 e as a result of the NWDAF 13 determining—after havingperformed step S302 c (or after step S302 e)—that the expiry time shouldhave a new value.

The PCF 14 thus sends an Nnwdaf_EventsSubscription_Update message to theNWDAF 13 in step S303 c in order to perform a handshake procedure asregards the changed expiry time as detected by the PCF 14 in step S303b, the message including: Slice instance ID, Analytic ID, User/Usergroup ID, New Period (based on the changed expiry time).

The NWDAF 13 acknowledges the request in step S303 d, and the PCF canfinally store the network analytics information and the new expiry timeassociated with the information, and optionally any Analytic ID, Sliceinstance ID and/or User/User group ID in step S304.

FIG. 7 shows a signalling diagram illustrating a method performed by anNWDAF 13 in a core network of providing, via a proxy 19, requestednetwork analytics information to the PCF 14 according to anotherembodiment. It is noted that the proxy 19 may be located inside theNWDAF 13 of even inside the PCF 14.

FIG. 7 illustrates a scenario where the PCF 14 performs arequest/response operation via the proxy 19.

In a first step S401 a, the PCF 14 sends a request to obtain networkanalytics information to the NWDAF 13 in the form of anNnwdaf_AnalyticsInfo_Request message including Analytic ID identifyingthe requested network analytics information, and optionally Sliceinstance ID and/or User/User group ID.

However, in this embodiment the request is sent to the proxy 19 whichstores the Analytic ID, the Slice instance ID and the User/User group IDin step S401 b and forwards the request Nnwdaf_AnalyticsInfo_Request tothe NWDAF 13 in step S401 c.

In response thereto, the NWDAF 13 determines in step S402 the expirytime for the requested network analytics information and sends in stepS403 a a response message to the PCF 14 including Analytic value andExpiry Time, where “Analytic value” denotes the actually requestedpayload network analytics information.

Again, this is passed via the proxy 19 which stores the requestednetwork analytics information and the expiry time in step S403 b, andmaps it to the previously stored Analytic ID, the Slice instance ID andthe User/User group ID, before forwarding the requested networkanalytics information to the PCF 14 in step S403 c, which stores it instep S404.

Now, assuming that another, third NF, for instance the NSSF 15, wishesto obtain the same network analytics information as was just deliveredto the PCF 14 and the proxy 19; the NSSF 15 will then send a request tothe proxy 19 in the form of an Nnwdaf_AnalyticsInfo_Request message tothe proxy in step S405 comprising the Analytic ID, the Slice instance IDand the User/User group ID.

If the expiry time has still not elapsed, the proxy 19 will return thestored requested network analytics information to the NSSF 15 in stepS406.

However, at a later instance, the NSSF 15 sends a further request to theproxy 19 in step S408 comprising the Analytic ID, the Slice instance IDand the User/User group ID.

At this point in time, the expiry time has elapsed, and the proxy 19 andthe NWDAF 13 will have to repeat steps S401 c-S403 b on behalf of theNSSF 15 such that the proxy 19 finally can send the requested networkanalytics information, and any expiry time associated with it, to theNSSF 14 in step S409.

Advantageously, the proxy 19 will act as a cache for storing requestednetwork analytics information. In this way, since the NFs make requeststo the proxy 19 while the proxy 19 handles the expiry time, the serviceconsumer implementations are not impacted and the signallingoptimization in the NWDAF is maintained. Unsuccessful

FIG. 8 illustrates a first core NF entity 13 according to an embodiment.The steps of the method performed by the first core NF entity 13 ofproviding requested network information to a second NF entity accordingto embodiments are in practice performed by a processing unit 115embodied in the form of one or more microprocessors arranged to executea computer program 116 downloaded to a suitable storage volatile medium117 associated with the microprocessor, such as a Random Access Memory(RAM), or a non-volatile storage medium such as a Flash memory or a harddisk drive. The processing unit 115 is arranged to cause the first coreNF entity 13 to carry out the method according to embodiments when theappropriate computer program 116 comprising computer-executableinstructions is downloaded to the storage medium 117 and executed by theprocessing unit 115. The storage medium 117 may also be a computerprogram product comprising the computer program 116. Alternatively, thecomputer program 116 may be transferred to the storage medium 117 bymeans of a suitable computer program product, such as a DigitalVersatile Disc (DVD) or a memory stick. As a further alternative, thecomputer program 116 may be downloaded to the storage medium 117 over anetwork. The processing unit 115 may alternatively be embodied in theform of a digital signal processor (DSP), an application specificintegrated circuit (ASIC), a field-programmable gate array (FPGA), acomplex programmable logic device (CPLD), etc.

The first core NF entity 13 comprises receiving means 140 adapted toreceive a request to obtain the network information originating from thesecond NF entity, determining means 141 adapted to determining an expirytime stipulating how long the requested network information is valid,and transmitting means 142 adapted to transmit, towards the second NFentity, the requested network information and the expiry time.

The means 140-142 may comprise communication interface(s) for receivingand providing information, and further a local storage for storing data,and may (in analogy with that previously discussed) be implemented by aprocessor embodied in the form of one or more microprocessors arrangedto execute a computer program downloaded to a suitable storage mediumassociated with the microprocessor, such as a RAM, a Flash memory or ahard disk drive.

FIG. 9 illustrates a second NF entity 14 according to an embodiment. Thesteps of the method performed by the second NF entity of obtainingnetwork information of a first core NF entity according to embodimentsare in practice performed by a processing unit 125 embodied in the formof one or more microprocessors arranged to execute a computer program126 downloaded to a suitable storage volatile medium 127 associated withthe microprocessor, such as a RAM, or a non-volatile storage medium suchas a Flash memory or a hard disk drive. The processing unit 125 isarranged to cause the second NF entity 14 to carry out the methodaccording to embodiments when the appropriate computer program 126comprising computer-executable instructions is downloaded to the storagemedium 127 and executed by the processing unit 125. The storage medium127 may also be a computer program product comprising the computerprogram 126. Alternatively, the computer program 126 may be transferredto the storage medium 127 by means of a suitable computer programproduct, such as a DVD or a memory stick. As a further alternative, thecomputer program 126 may be downloaded to the storage medium 127 over anetwork. The processing unit 125 may alternatively be embodied in theform of a DSP, an ASIC, a FPGA, a CPLD, etc.

The second NF entity 14 comprises transmitting means 150 adapted totransmit, towards the first core NF entity, a request to obtain thenetwork information, and receiving means 151 adapted to receive therequested network information and an expiry time determined by the firstcore NF entity stipulating how long the requested network information isvalid.

The means 150 and 151 may comprise communications interface(s) forreceiving and providing information, and further a local storage forstoring data, and may (in analogy with that previously discussed) beimplemented by a processor embodied in the form of one or moremicroprocessors arranged to execute a computer program downloaded to asuitable storage medium associated with the microprocessor, such as aRAM, a Flash memory or a hard disk drive.

FIG. 10 illustrates a proxy device 19 according to an embodiment. Thesteps of the method performed by the proxy device 19 of providingrequested network information of a first core NF entity to a second NFentity according to embodiments are in practice performed by aprocessing unit 135 embodied in the form of one or more microprocessorsarranged to execute a computer program 136 downloaded to a suitablestorage volatile medium 137 associated with the microprocessor, such asa RAM, or a non-volatile storage medium such as a Flash memory or a harddisk drive. The processing unit 135 is arranged to cause the proxydevice 19 to carry out the method according to embodiments when theappropriate computer program 136 comprising computer-executableinstructions is downloaded to the storage medium 137 and executed by theprocessing unit 135. The storage medium 137 may also be a computerprogram product comprising the computer program 136. Alternatively, thecomputer program 116 may be transferred to the storage medium 137 bymeans of a suitable computer program product, such as a DigitalVersatile Disc (DVD) or a memory stick. As a further alternative, thecomputer program 136 may be downloaded to the storage medium 137 over anetwork. The processing unit 135 may alternatively be embodied in theform of a digital signal processor (DSP), an application specificintegrated circuit (ASIC), a field-programmable gate array (FPGA), acomplex programmable logic device (CPLD), etc.

The proxy device 19 comprises receiving means 160 adapted to receive,from the second NF entity, a request to obtain the network information,transmitting means 161 adapted to transmit, to the first core NF entity,the request to obtain the network information, receiving means 162adapted to receive, from the first core NF entity, the requested networkinformation and an expiry time determined by the first core NF entitystipulating how long the requested network information is valid, andtransmitting means 163 adapted to transmit, to the second NF entity, therequested network information.

The means 160-163 may comprise communication interface(s) for receivingand providing information, and further a local storage for storing data,and may (in analogy with that previously discussed) be implemented by aprocessor embodied in the form of one or more microprocessors arrangedto execute a computer program downloaded to a suitable storage mediumassociated with the microprocessor, such as a RAM, a Flash memory or ahard disk drive.

The invention has mainly been described above with reference to a fewembodiments. However, as is readily appreciated by a person skilled inthe art, other embodiments than the ones disclosed above are equallypossible within the scope of the invention, as defined by the appendedpatent claims.

The invention claimed is:
 1. A method performed by a requesting NetworkFunction, NF, entity for obtaining network information from a respondingcore NF entity: transmitting towards the responding core NF entity, arequest to obtain the network information; and receiving the requestednetwork information and an expiry time determined by the responding coreNF entity stipulating how long the requested network information isvalid.
 2. The method of claim 1, wherein the requesting NF entity isconfigured to refrain from making another request for said networkinformation as long as the expiry time has not elapsed.
 3. The method ofclaim 1, further comprising: storing the received network informationand the expiry time.
 4. The method of claim 1, wherein the requestfurther being configured to comprise at least one of: at least oneidentifier identifying a network slice instance for which the request ismade, and at least one identifier identifying a user device or a groupof user devices for which the request is made.
 5. The method of claim 1,wherein the request further being configured to comprise an indicationof periodicity with which the request network information is to beobtained.
 6. The method of claim 1, further comprising: receiving amessage from the responding core NF entity comprising a recommendedperiodicity stipulated by the determined expiry time; and transmitting aconfirmation to the responding core NF entity indicating whether therecommended periodicity stipulated by the determined expiry time shouldbe used or not.
 7. The method of claim 1, further comprising: receivingan update message from the responding core NF entity in case it isdetermined that the expiry time for the requested network informationhas changed, the update message comprising a recommended periodicitystipulated by the determined changed expiry time; and transmitting aconfirmation to the responding core NF entity indicating whether therecommended periodicity stipulated by the determined changed expiry timeshould be used or not.
 8. The method of claim 1, wherein the request tothe responding core NF entity to obtain the network information istransmitted via a proxy device from which the requested networkinformation and the expiry time are subsequently received.
 9. Arequesting Network Function, NF, entity configured to obtaining networkinformation of a responding core NF entity, the requesting NF entitycomprising a processing unit and a memory, said memory containinginstructions executable by said processing unit, whereby the requestingNF entity is operative to: transmit towards the responding core NFentity, a request to obtain the network information; and to receive therequested network information and an expiry time determined by theresponding core NF entity stipulating how long the requested networkinformation is valid.
 10. The requesting NF entity of claim 9, whereinthe requesting NF entity is configured to refrain from making anotherrequest for said network information as long as the expiry time has notelapsed.
 11. The requesting NF entity of claim 9, further beingoperative to: store the received network information and the expirytime.
 12. The requesting NF entity of claim 9, the request further beingconfigured to comprise at least one of: at least one identifieridentifying a network slice instance for which the request is made, andat least one identifier identifying a user device or a group of userdevices for which the request is made.
 13. The requesting NF entity ofclaim 9, the transmitted request further being configured to comprise anindication of periodicity with which the request network information isto be obtained.
 14. The requesting NF entity of claim 13, further beingoperative to: receive a message from the responding core NF entitycomprising a recommended periodicity stipulated by the determined expirytime; and to transmit a confirmation to the responding core NF entityindicating whether the recommended periodicity stipulated by thedetermined expiry time should be used or not.
 15. The requesting NFentity of claim 13, further being operative to: receive an updatemessage from the responding core NF entity, in case it is determinedthat the expiry time for the requested network information has changed,the update message comprising a recommended periodicity stipulated bythe determined changed expiry time; and to transmit a confirmation tothe responding core NF entity indicating whether the recommendedperiodicity stipulated by the determined changed expiry time should beused or not.
 16. The requesting NF entity of claim 9, wherein therequest to the responding core NF entity to obtain the networkinformation is transmitted via a proxy device from which the requestednetwork information and the expiry time are subsequently received.